1. Field
Example embodiments relate to an ink discharge apparatus to discharge uniform amounts of transparent ink droplets and a method of controlling the same.
2. Description of the Related Art
An ink discharge apparatus discharges a desired amount of ink droplets at a desired position on a printing medium. The ink discharge apparatus includes an inkjet head having a plurality of nozzles to discharge ink droplets.
In order to manufacture a high quality Liquid Crystal Display (LCD) panel in a printing process using an inkjet head, ink needs to be uniformly applied to the LCD panel. The ink may be uniformly applied by uniformly adjusting the amount of ink droplets discharged from the plurality of nozzles of the head. That is, making the amount of ink droplets discharged from the inkjet head uniform is necessary for manufacture of a high quality LCD panel using an inkjet head.
In general, in a panel printed by applying the same signal to the nozzles of the inkjet head, a difference between the amounts of ink droplets discharged from nozzles may be visually recognized as a stain by an inspector. That is, even when the same signal is applied, the same amount of ink droplets may not be discharged due to differences in the characteristics of the nozzles of the inkjet head. Accordingly, the amounts of ink droplets discharged from the respective nozzles are accurately measured and voltages applied to the nozzles are changed based on the measured amounts such that the ink droplets are uniformly discharged. Such a process is generally referred to as Driver per Nozzle (DPN).
In a DPN process of the related art, a method of measuring a difference between color values according to the amount of ink is used to measure the amounts of ink discharged from nozzles. In this method, in the case of color ink, since the thickness of applied ink varies according to the amount of ink discharged and a color value varies according to the thickness of applied ink, the amount of applied ink may be extrapolated from the color value. However, in the case of transparent ink, since a color value is not changed according to the thickness of applied ink, it is difficult to measure a difference between the amounts of discharged inks. If the thickness of the transparent ink is measured using a thin-film thickness measurement device of the related art, it takes considerable time to measure the thickness of the transparent ink and to perform a DPN process.